Various types of measuring instruments are used for measuring distances and angles between objects. Here, several conventional measuring instruments, such as surveying instruments, for example, use a laser light source for measuring the distance from or the position of an object by carrying out an electro-optical measurement.
A special measuring instrument, the leveling apparatus or laser leveling apparatus, can measure, for example, with the aid of a measuring rule, differences in height and establish height horizons. For example, a leveling apparatus comprises a targeting telescope which, using a level or a pendulum compensator, can be oriented perpendicularly to the plumb line direction. In addition to the measurement of positions, particularly of differences in height, horizontal surfaces or vertical surfaces can also be established.
To measure distance or position, the user must verify that the laser beam of the laser light source actually impinges on the object at a desired position. However, a laser point which impinges, for example, on a wall, is usually very small, and in a Z mode (i.e., a through beam is horizontal and a deflected beam orthogonal to said through beam), in the case of a large distance, a user may have difficulties finding the laser point with the naked eye or with a conventional photodetector. In addition, the intensity of the laser beam decreases over the distance, so that the intensity of the light that is scattered back by the wall decreases further.
Therefore it can be very expensive and sometimes even impossible to find the laser point with the eye or by moving a photodetector in a target area, owing to the small size of the laser point and of the distance from the laser source.
Furthermore, finding a small laser point becomes even more complicated under outside conditions in the field, such as, for example, ambient light, snow, rain and wind, where a rapid and reliable detection is desirable.
A positioning device and a positioning method that make it possible to find a center of a laser beam more rapidly and more easily, particularly by using a fanned laser beam or fan-like laser beam, is described, for example, in the German patent application having the reference DE 11 2008 003 912.7.
The generation of a fanned laser beam is, however, not trivial. Since a measurement of a distance or a measurement of an angle is not possible with a fanned laser beam or a similarly uncollimated light beam, one must provide either different light sources for the fanned laser beam and an unchanged laser beam, or a way has to be found to introduce an optical element into the laser beam and remove it therefrom, as needed. Such a mechanism is not only helpful in generating a fanned laser beam, but it can also be used to change the propagation direction of a laser beam or other optical properties.
A laser beam which has been fanned out by swiveling in a cylindrical lens can generate a light cone by rotation of the cylindrical lens in the laser beam, so that, using an appropriate emission device for a light beam or for a laser beam, several basic conditions with regard to geometry and user friendliness have to be taken into consideration.
There is a need therefore to provide a light beam emission device for a measuring instrument and a corresponding method which make it possible to change the optical properties of a light beam in a simple and reproducible manner.